The use of lamellar effect pigments, such as mica pigments or metallic effect pigments, in solventborne basecoat materials per se is long-established practice.
On account of their comparatively high sensitivity to mechanical exposure, however, lamellar effect pigments, more particularly mica pigments and metallic effect pigments, especially aluminum pigments, present problems on incorporation into solventborne coating materials, more particularly solventborne basecoat materials. European patent applications EP 1 504 068 A1, EP 1 534 792 B1 and EP 1 799 783 A1 describe storage-stable, water-based mica, metallic and/or aluminum effect pigment pastes. European patent applications EP 0 578 645 B1, EP 0 662 993 B1 and EP 0 752 455 B1 describe storage-stable, solvent-based mica, metallic and/or aluminum effect pigment pastes.
The mica and metallic effect pigments are typically pasted up or dispersed in organic solvents. A disadvantage is that the pigment pastes in question have only a very limited storage life, amounting to a few hours or days at most. After this time, settling occurs, and bits and coagulum are formed, diminishing the quality of the multicoat color and/or effect paint systems as a result, among other things, of clouding effects. The brevity of storage life is also a major problem for large-scale finishing on the line at the automaker. For instance, the production, for holding in stock, of relatively large quantities of pigment pastes, which would be desirable on economic grounds, is not possible. Problems with transportability, such as the low stability on storage, for example, remove the possibility for the pigment pastes to be produced at a production site with optimum production conditions and transported to the customers. Accordingly, for the tinting of solventborne basecoat materials, the pigment pastes have to be produced anew each time, which complicates and slows down the production process.
Accordingly, a new solventborne pigment paste, comprising lamellar effect pigments, which no longer has the disadvantages of the prior art but instead can be produced simply, stably, storably, transportably and without damage to the lamellar effect pigments is desired. The new solventborne pigment paste comprising lamellar effect pigments is preferably to be storable for up to 3 months without settling and without formation of bits and coagulum, and is to be reagitatable.